Multiple rendering engines may sample a specific pixel (e.g., at different times). However, if the rendering engines are controlled to sample the specific pixel at different locations of that pixel (e.g., by virtue of the locations being identified by differing random sequences), it is more likely that a sampled color for that pixel will be provided more quickly. A convergence speed of that pixel may be improved based on multiple rendering engines potentially sampling the pixel in conjunction with each other (as compared to a situation in which only a single rendering engine samples the pixel).

As described earlier, a separate merge process (e.g., merger 140) merges rendering results generated by each of multiple rendering engines (e.g., rendering engines 130) into a single image for transmission back to a front-end host (e.g., client 110) for display. The merge process may be performed by using a merge-filter function which is defined for each image. The merge-filter function may specify, for example, how to merge rendering results corresponding to a particular pixel of the image into a resulting pixel (e.g., a composite pixel) that is for display. Based on the merge-filter function, the merge process merges rendering results for the particular pixel, which are received from the rendering engines.